1. Field of the Invention
The present invention relates to a method of and an apparatus for processing a semiconductor substrate, a liquid crystal glass substrate, or the like (hereinafter referred to simply as "substrate").
2. Description of the Background Art
Various types of treatments are performed on a substrate during steps of manufacturing a semiconductor substrate, a liquid crystal glass substrate, etc. The treatments include coating of a substrate with a photoresist, stripping of a photoresist, cleaning after stripping of a photoresist, etc. In the following, a description will be given of a substrate processing apparatus for cleaning a substrate, with reference to FIG. 11 which shows an essential cross sectional view of the substrate processing apparatus. The illustrated substrate processing apparatus is an apparatus proposed in Japanese Utility Model Application Laid-Open Gazette No. 5-20321.
A substrate processing apparatus 1 uses a chemical liquid, such as fluoric acid, and de-ionized water as a cleaning fluid to clean a substrate.
The substrate processing apparatus 1 includes a chamber 9 within a box-like member 8. A drain outlet 10 for draining the cleaning fluid is disposed in a lower portion of the chamber 9. The chamber 9 houses substrate holding means 11 for holding, by suction, a substrate W. The substrate holding means 11 is rotated by rotating means (not shown). Further, the chamber 9 houses a cleaning fluid injecting nozzle 12 for supplying the cleaning fluid onto the substrate W and a gas supply nozzle 13 for supplying inert gas into the chamber 9.
Processing of the substrate W within the substrate processing apparatus 1 is subsequently described. First, the substrate W is placed on the substrate holding means 11, and the substrate holding means 11 holds, by suction, the substrate W. Next, the substrate holding means 11 is rotated by the rotating means. On the other hand, the gas supply nozzle 13 gushes inert gas toward the substrate W so that an area in the vicinity of a surface of the substrate W is filled with the inert gas. This is to ensure that the substrate W is processed in the atmosphere which does not contain air but is filled with the inert gas, to thereby prevent an undesirable oxide film from forming on the substrate W. Further, the cleaning fluid injecting nozzle 12 gushes the cleaning fluid toward the substrate W which is being rotated. Hence, the substrate W is cleaned with the cleaning fluid within the atmosphere with the inert gas. Excess of the cleaning fluid dripping from the substrate W is drained through the drain outlet 10 which is disposed in a lower portion of the chamber 9.
Further, an apparatus disclosed in U.S. Pat. No. 790,567 includes a chamber which contains a substrate holding means for holding a substrate, a fluid flow guide arranged in the upper part of the substrate holding means so as to face a substrate, and a central conduit arranged in the center of the fluid flow guide.
In the substrate processing apparatus described above, a processing fluid is supplied through the central conduit to the surface of the substrate. After the fluid supply stops, an inert gas is supplied to the surface of the substrate, to prevent the substrate from being polluted by air.
In the conventional substrate processing apparatus 1, as the substrate W is rotated, an air flow which whirls upward is created at the surface of the substrate W, as shown in FIG. 11, resulting in a turbulence T. The turbulence T disturbs pollutants within the chamber 9 and causes the pollutants to adhere to the substrate W. As a result, the quality of the substrate is inconveniently deteriorated.
Further, while the gas supply nozzle 13 blows the inert gas toward the substrate W to prevent formation of an oxide film, a large space above the substrate W causes a large quantity of air to be included in the inert gas when the inert gas reaches the substrate W. For this reason, it is necessary to supply a large quantity of the inert gas to minimize air which exists near the surface of the substrate W, which leads to an increase in the opperating cost of the apparatus.
Further, while the processing fluid is supplied to the surface of a substrate and directly after the supply stops, an inert gas film cannot be formed. For this reason, an oxide film is likely to be formed on the surface of a substrate by being exposed to air.